Chapter 0

Reader's manual

Python is a high level programming language. A high level programming language is a computer programming language that allows you to express business logic in an almost natural way using plain English language. This is text, closer to human readable language than binary machine language. Python is a structured programming language, allowing you to structure the code logic in statements, blocks, units and classes, modules and to reuse them as building blocks of your solution.

Python is an interpreted programming language. Python is a native executable that allows you to input the program line by line, interpreting each line of code. Even if you launch Python in headless mode, the code will be interpreted line by line from the source file. This allows fast fail execution and it is easy to follow runtime errors.

Python is an Object Oriented Programming (OOP) language. Conceived in the late '80s, Python learned from previous OOP languages like Java and C++, and had a healthy approach with simplicity in mind. It incorporates also concepts from: imperative programming, functional programming, procedural programming and has several compilers for Java, C, .NET, Go. Python is versatile and rich, it is an excellent choice for learning a programming language.

Python is a tool, use it wisely!

How to read this book?

This is companion material, so you need a couple of external tools in order to have a successful journey. First, you will need a computer. You may install Python 3.X on you computer. Python interpreter runs on a variety of processor architectures and operating systems: desktop, laptop, Raspberry PI, tablets, cloud, fridges etc. You will need an Internet connection. The you will need a good text editor or IDE. I will not make any suggestions since this will be your tool and you should be comfortable with it - make your own choice after trying a couple of editors. The result will always be the same no matter which tool you are using.

You will need to have this book open so that you can follow the steps described here and obtain the same results on your machine. The book is linear, so you start with Chapter I and carry on. The goal of each chapter is stated from the beginning and it should be clear for you if you attained or not the objective. Each step will introduce parts of Python language and concepts of Operating Systems. You will have a sort of homework after each chapter. The main purpose is to learn how software solutions are developed incrementally, but you are encouraged to build you own solution or to use some other frameworks to build the solution. In the end all that matters is that you will be able to understand a human written business requirement and implement it in Python.

The code can be found on github: https://github.com/dragos-constantin-stoica/python_book

Each chapter has its own folder, the code can be run independently of the others chapters.

I will use Repl.it (https://repl.it/) to run the code directly from Github. All the results of code execution in the book are from Repl.it. Some good alternatives are: local installation of Python, a VM on local machine or remote, a container, or other online service like https://codetasty.com/, https://codenvy.com/, https://paiza.io/en/languages/python3, https://ideone.com/.